Known from U.S. Pat. No. 7,624,547 (B1) is a skylight designed for mounting on a framing protruding from the roof, fitted with a glazing unit comprising two panes connected with a spacer frame. The glazing unit is secured by means of a frame overlapping the upper surface of the outer pane. This solution hinders the flow of rain water or water from melted snow down the pane, because water collects at the frame protruding above the window pane at the glazing unit's lower edge. This collection of runoff occurs especially in windows installed on flat roofs or those with only a mild incline.